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Diesel vs. Hybrid: A Point Missed

Steve,

Thanks for posting the links.
As you know, they're for 2002 Jettas. From what I've read, VW has much improved on their quality since 2002. One blogger noted on how unsafe his car was. Iím not sure how the new Jetta fares against the older models, but the new Passat is rated as one of the safest models currently available (though the TDI version isn't available in the US yet). I'm not saying not to be wary, but I am saying that a lot of the bad stigma against VW isn't necessarily true anymore.

Diesel vs. Hybrid: A Point Missed

Tim,

Your opinion about "sponsoring terrorists by using diesel" has nothing to do with reality. It's not that you can produce either gasoline or diesel out of crude oil -- oil refinery gives out both gasoline and diesel as well as many other products. The outcome of diesel is usually higher than for gasoline and the process is cheaper (here you are right). Diesel cars also consume less than the gasoline rivals per km(or mile) driven. In the end, you need to buy less oil to drive longer, if you use a diesel car.

And if you really worry about terrorism, then why not also asking your administration, why CIA has supported with arms and sponsered Talibs in Afagnistan (Osama Bin Laden eventually creates Al Caida and trains bustards that later fly into WTC in NY), Saddam in Irak some time ago. The world is not black and white, it's far more complex.

Diesel vs. Hybrid: A Point Missed

To Steve in Georgia
Yes I can show you that diesel car that last.
Take a trip to Norway and visit my brother.
His 94 C-class diesel Benz has 490000km on
the odometer (thats 308000miles). The only big
repair he did was to change clutch. It does not
burn oil, starts in the cold winters at latitude 62.
There was no diesel smoke coming out of the tail
pipe when I last drove the car in the fall of 05.

Diesel vs. Hybrid: A Point Missed

The used car listings aren't a valid statistical method to gain data on diesel longevity. First of all, VW diesels weren't sold in the US from 1992-1996; that limits the sample size of diesels that have really high mileage: to have 500k miles, a '96 Passat TDI (the only VW diesel available in the US that year) would have to have been driven 50k miles per year since new. I would be prepared to venture an educated guess that very few cars have done that. The earlier diesels would probably not figure highly either, simply due to old age. Especially in the northeast rust belt, a pre-90 car no matter the mileage is likely to be a rustbucket.

Secondly the statistical sample sizes for diesel vs. gasoline are hugely different (at least for cars); in the US, diesels are an insignificant part of the market: approx. 5% of VW's sales. In Canada the market is slightly larger; 40-50% of VW sales, but that's still very small compared to the gas market.

Thirdly, because of their longevity, many people actually keep their diesels until they're junk, rather than trade them in. Their excellent fuel economy also makes them quite scarce on the used market. In Canada it's not unusual for a used TDI to scoot off the lot the same day it's put up for sale.

To be valid you would have to look at what percentage of diesels, vs. gas, make it past 100k, 200k, 300k, 400k, etc.

It might be helpful to look at Canadian used vehicle sites. Unlike the US, VW sold diesels continuously in Canada since the first Rabbit diesel. It's not unusual for a mid-90's diesel with 300,000 km to sell for about $5000 CDN up here, if the body is still solid.

Diesel vs. Hybrid: A Point Missed

"The used car listings aren't a valid statistical method to gain data on diesel longevity"

Used car listings are indeed a good indicator of how long cars last.
If gasoline car listings show hundreds of cars from several MFG's for sale with 150-400K mile range, it says one thing.
If diesel car lines have dramatically less vehicles with the same mile range it says another thing.

If diesel cars lasted 500K miles on average or even close, we'd see quite a large number of +30 year old models still on the road.

I've provided links to respected automobile listings and consumer guides in my research to show that diesel autos don't last as long and are problematic.

Diesel vs. Hybrid: A Point Missed

Have you normalized your statistics as a percentage of diesel vs. gas market share for the model year of the cars you're considering?

You can't rely on raw numbers if you're comparing a product that has, at best, a 5% market share with one that has a 95% market share. Another flaw in your study is that you are assuming that the engine is the reason for the car's ultimate failure; in Canada it's usually the body/chassis, due to corrosion damage (salt on the roads) and in the US there could be other reasons.

I looked at the Canadian Autrader site and limited my search to Quebec, the diesel car capital of Canada; I filtered out Hondas and VW diesels asking for those with 200,000 km or more, and then I looked to see how many in that batch had 300,000 or more. I found that 7% of the Hondas (all models) I pulled up had more than 300k (6 of 82 listings), but 14% of the VW diesels with the same filter criteria had 300k or more (3 of 21 listings). Roughly speaking, 82 listings for Honda and 21 for VW (diesels only) would be representative of their respective market shares. But I admit the sample size is very small.

Overall, for Hondas of all makes I pulled up 82 listings with over 200k, for VW, 60 listings of all models (gas and diesel) of which only 1 gas model made it over 300k. One can say that the longevity rate of VW vs Honda is about the same (7% of my sample being over 300k), but that the VW longevity is significantly boosted by the diesels (3 of the 4 listings with over 300k were diesels).

Nationwide, 17.6% of the diesels with over 200,000 had over 300,000.

One should probably look into the European situation where the greater sample size would be helpful. You will find very few non-diesel taxis in Europe, which is telling.

Finally, much of the US sample would probably distorted by the notorious GM diesels of the late 70s/early 80s, where GM attempted to stick a diesel head on a gasoline block with disastrous results (and in fact largely contributed to the loss of diesel's appeal in the US).

I would say that the Canadian results, in spite of rust tending to be the limiting factor in car life, indeed points to the diesels being better for longevity, at least from the small sampling I took.

Diesel vs. Hybrid: A Point Missed

Its amazing that this debate on longevity takes
place (diesel versus gasoline). There are so few diesels in the US made by a decent diesel manufacturer such as MB,VW,Audi or BMW that
there are no stats available, but any mechanic in
Europe can tell you diesel cars last twice as long
and have very few maintenance issues.

Diesel vs. Hybrid: A Point Missed

You are again making the mistake of assuming that ultimate failure of the engine is the reason that a car is sent to the junkyard.

In Canada that would be very unlikely; utlimately the bodies and chassis fail due to corrosion. In other parts of the world, other wear-and-tear items will be the cause of the demise, such as the transmission and major suspension components.

Another factor to consider is that engines can be rebuilt. In your survey of gas vs diesel longevity, how many of those gas engines, on older high-mileage cars, have been rebuilt vs the diesels?

Interestingly, Cuba has a number of old jalopies on the road, classics from the 50s. No doubt the engines in those have been rebuilt many times over, for those that drive serious mileage. The climate has been kind to the bodies, and lack of availability of any decent replacement makes it economical to rebuild. In our throw-away society, most will simply toss a car if a major component like a gearbox or engine fails on a 20 y.o. car with over 200,000 miles.

The cars that could probably compete with diesels for longevity, were the older American V8s. Why? Typically these engines, like diesel auto engines, rev at around 2000 rpm or less at 60 mph.

I know a good old country doctor who kept his Mercedes 300d (both he and the car now rest in peace), for 300,000+ miles without an engine rebuild, before body corrosion forced retirement.

Anecdotal? Yes, but so is your "statistical" analysis pulled from an Internet used car site.